Tree swallow (Tachycineta bicolor) and house wren (Troglodytes aedon) eggs and chicks were collected near a refinery site on the North Platte River, Casper. Wyoming, USA and at a reference site 10 km upstream. Total polycyclic aromatic hydrocarbon (PAH) concentrations in swallow and wren chicks were higher at the refinery site than at the reference site. Polycyclic aromatic hydrocarbon concentrations in sediment and chick dietary samples were consistent with these findings. The general lack of methylated PAHs in sediment, diet, and bird carcasses suggested that the PAHs were derived from combustion and not from petroleum. The predominance of odd-numbered aliphatic hydrocarbons and the low ratios (< or =0.25) of pristane:n-C17 and phytane:n-C18 in chick and diet samples also suggested that swallow and wren chicks were not being chronically exposed to petroleum. Mean ethoxyresorufin-O-dealkylase and benzyloxyresorufin-O-dealkylase activities in tree swallow livers averaged nine times higher at the refinery site than at the reference site and were probably induced by exposure to PAHs. Trace element concentrations in eggs and livers of swallows and wrens were similar or greater at the reference site than at the refinery site. Selenium, strontium, and boron concentrations were elevated in eggs and livers of swallows and wrens at both the refinery and reference sites.
Most of the polychlorinated biphenyl (PCB) body burden
accumulated by coho salmon (Oncorhynchus kisutch) from
the Laurentian Great Lakes is from their food. We used
diet information, PCB determinations in both coho salmon
and their prey, and bioenergetics modeling to estimate
the efficiency with which Lake Michigan coho salmon retain
PCBs from their food. Our estimate was the most
reliable estimate to date because (a) the coho salmon
and prey fish sampled during our study were sampled in
spring, summer, and fall from various locations throughout
the lake, (b) detailed measurements were made on the
PCB concentrations of both coho salmon and prey fish over
wide ranges in fish size, and (c) coho salmon diet was
analyzed in detail from April through November over a wide
range of salmon size from numerous locations throughout
the lake. We estimated that coho salmon from Lake
Michigan retain 50% of the PCBs that are contained within
their food.
Most of the polychlorinated biphenyl (PCB) body burden
accumulated by lake trout (Salvelinus
namaycush)
from
the Laurentian Great Lakes is from their food. We used
diet
information, PCB determinations in both lake trout and
their prey, and bioenergetics modeling to estimate the ef
ficiency with which Lake Michigan lake trout retain PCBs
from their food. Our estimates were the most reliable
estimates to date because (a) the lake trout and prey
fish sampled during our study were all from the same
vicinity
of the lake, (b) detailed measurements were made on
the PCB concentrations of both lake trout and prey fish
over
wide ranges in fish size, and (c) lake trout diet was
analyzed in detail over a wide range of lake trout size.
Our
estimates of net trophic transfer efficiency of PCBs to
lake trout from their prey ranged from 0.73 to 0.89 for
lake
trout between the ages of 5 and 10 years old. There
was
no evidence of an upward or downward trend in our
estimates
of net trophic transfer efficiency for lake trout between
the ages of 5 and 10 years old, and therefore this
efficiency
appeared to be constant over the duration of the lake
trout's adult life in the lake. On the basis of our
estimates,
lake trout retained 80% of the PCBs that are contained
within their food.
We tested the hypothesis that the efficiency with which
fish retain polychlorinated biphenyl (PCB) congeners from
their food strongly depends on K
ow and degree of
chlorination of the congener. We used diet information,
determinations of concentrations of individual PCB congeners
in both coho salmon (Oncorhynchus kisutch) and their
prey, and bioenergetics modeling to estimate the efficiencies
with which Lake Michigan coho salmon retain various
PCB congeners from their food. The retention efficiency
for the tetrachloro congeners averaged 38%, whereas
retention efficiencies for higher chlorinated congeners
ranged from 43 to 56%. Not including tetrachloro congeners,
we found neither decreasing nor increasing trends in
the efficiencies with which the coho salmon retained the
PCB congeners from their food with either increasing
K
ow or increasing degree of chlorination of the PCB congeners.
We concluded that (a) for PCB congeners with 5−8
chlorine atoms/molecule, K
ow and degree of chlorination
had little influence on the efficiency with which coho salmon
retained the various PCB congeners in their food, and
(b) the efficiency with which coho salmon retained tetrachloro
PCB congeners in their food appeared to be slightly
lower than that for higher chlorinated PCB congeners.
This paper reviews opportunities and watershed restoration tech niques available for rehabilitating and enhancing riparian ecosystems in southwest environments. As such, it is intended to serve as a state of-the-art report on riparian hydrology and improvement in both naturally occurring and man-made riparian areas throughout the Southwest. NPS RESEARCH LIBRARY 1HeadQu.arters is in. Fort~/AMJl"c.At.t¥GtJitNA,1!,ldj)AR~nIVerSlty. DeBano is stationed In Tempe, In cooWJIi1Al'?,it""""zona ~1ate lMfversl1y:
Phase 1 Transport (sand & finer gravel) typically supply-limited Bedload transport rate (tons/day) Flow frequency (days) Total bedload transport (tons) RANGE OF CHANNEL MAINTENANCE FLOWS Moves 100% of bedload mass Q threshold Q trigger Q effective Q cap Phase 2 Transport (gravel and larger sizes) typically transport-limited You may order additional copies of this publication by sending your mailing information in label form through one of the following media. Please specify the publication title and series number.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.